/*
 *  linux/kernel/vsprintf.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 */

/* vsprintf.c -- Lars Wirzenius & Linus Torvalds. */
/*
 * Wirzenius wrote this portably, Torvalds fucked it up :-)
 */

#include <stdarg.h>
#include <string.h>

/* we use this so that we can do without the ctype library */
#define is_digit(c) ((c) >= '0' && (c) <= '9')

static int skip_atoi(const char **s)
{
    int i = 0;

    while (is_digit(**s)) {
        i = i * 10 + *((*s)++) - '0';
    }
    return i;
}

#define ZEROPAD 1       /* pad with zero */
#define SIGN    2       /* unsigned/signed long */
#define PLUS    4       /* show plus */
#define SPACE   8       /* space if plus */
#define LEFT    16      /* left justified */
#define SPECIAL 32      /* 0x */
#define SMALL   64      /* use 'abcdef' instead of 'ABCDEF' */

#define do_div(n,base) ({ \
        int __res; \
        __asm__("divl %4":"=a" (n),"=d" (__res):"0" (n),"1" (0),"r" (base)); \
        __res; })

static char * number(char *str,
        int num,
        int base,
        int size,
        int precision,
        int type)
{
    char c, sign, tmp[36];
    const char *digits = "0123456789ABCDEFGHIJKLMNOPQRSTUVWXYZ";
    int i;

    if (type & SMALL) {
        digits = "0123456789abcdefghijklmnopqrstuvwxyz";
    }
    if (type & LEFT) {
        type &= ~ZEROPAD;
    }
    if (base<2 || base>36) {
        return 0;
    }
    c = (type & ZEROPAD) ? '0' : ' ' ;
    if (type & SIGN && num < 0) {
        sign = '-';
        num = -num;
    } else {
        sign = (type & PLUS) ? '+' : ((type & SPACE) ? ' ' : 0);
    }
    if (sign) {
        size--;
    }
    if (type & SPECIAL) {
        if (base == 16) {
            size -= 2;
        } else if (base == 8) {
            size--;
        }
    }
    i = 0;
    if (num == 0) {
        tmp[i++] = '0';
    } else {
        while (num != 0) {
            tmp[i++] = digits[do_div(num, base)];
        }
    }
    if (i > precision) {
        precision = i;
    }
    size -= precision;
    if (!(type & (ZEROPAD + LEFT))) {
        while (size-- > 0) {
            *str++ = ' ';
        }
    }
    if (sign) {
        *str++ = sign;
    }
    if (type & SPECIAL) {
        if (base == 8) {
            *str++ = '0';
        } else if (base == 16) {
            *str++ = '0';
            *str++ = digits[33];
        }
    }
    if (!(type & LEFT)) {
        while (size-- > 0) {
            *str++ = c;
        }
    }
    while (i < precision--) {
        *str++ = '0';
    }
    while (i-- > 0) {
        *str++ = tmp[i];
    }
    while (size-- > 0) {
        *str++ = ' ';
    }
    return str;
}

int vsprintf(char *buf, const char *fmt, va_list args)
{
    int len;
    int i;
    char *str;
    char *s;
    int *ip;

    int flags;      /* flags to number() */

    int field_width;    /* width of output field */
    int precision;      /* min. # of digits for integers; max
                           number of chars for from string */
    int qualifier;      /* 'h', 'l', or 'L' for integer fields */

    for (str = buf ; *fmt ; ++fmt) {
        if (*fmt != '%') {
            *str++ = *fmt;
            continue;
        }

        /* process flags */
        flags = 0;
repeat : ++fmt;      /* this also skips first '%' */
         switch (*fmt) {
             case '-':
                 flags |= LEFT; goto repeat;
             case '+':
                 flags |= PLUS; goto repeat;
             case ' ':
                 flags |= SPACE; goto repeat;
             case '#':
                 flags |= SPECIAL; goto repeat;
             case '0':
                 flags |= ZEROPAD; goto repeat;
         }

         /* get field width */
         field_width = -1;
         if (is_digit(*fmt)) {
             field_width = skip_atoi(&fmt);
         } else if (*fmt == '*') {
             /* it's the next argument */
             ++fmt;
             field_width = va_arg(args, int);
             if (field_width < 0) {
                 field_width = -field_width;
                 flags |= LEFT;
             }
         }

         /* get the precision */
         precision = -1;
         if (*fmt == '.') {
             ++fmt;  
             if (is_digit(*fmt)) {
                 precision = skip_atoi(&fmt);
             } else if (*fmt == '*') {
                 /* it's the next argument */
                 precision = va_arg(args, int);
             }
             if (precision < 0) {
                 precision = 0;
             }
         }

         /* get the conversion qualifier */
         qualifier = -1;
         if (*fmt == 'h' || *fmt == 'l' || *fmt == 'L') {
             qualifier = *fmt;
             ++fmt;
         }

         switch (*fmt) {
             case 'c':
                 if (!(flags & LEFT)) {
                     while (--field_width > 0) {
                         *str++ = ' ';
                     }
                 }
                 *str++ = (unsigned char) va_arg(args, int);
                 while (--field_width > 0) {
                     *str++ = ' ';
                 }
                 break;

             case 's':
                 s = va_arg(args, char *);
                 len = strlen(s);
                 if (precision < 0) {
                     precision = len;
                 } else if (len > precision) {
                     len = precision;
                 }

                 if (!(flags & LEFT)) {
                     while (len < field_width--) {
                         *str++ = ' ';
                     }
                 }
                 for (i = 0; i < len; ++i) {
                     *str++ = *s++;
                 }
                 while (len < field_width--) {
                     *str++ = ' ';
                 }
                 break;

             case 'o':
                 str = number(str,
                         va_arg(args, unsigned long),
                         8,
                         field_width,
                         precision,
                         flags);
                 break;

             case 'p':
                 if (field_width == -1) {
                     field_width = 8;
                     flags |= ZEROPAD;
                 }
                 str = number(str,
                         (unsigned long) va_arg(args, void *),
                         16,
                         field_width,
                         precision,
                         flags);
                 break;

             case 'x':
                 flags |= SMALL;
             case 'X':
                 str = number(str,
                         va_arg(args, unsigned long),
                         16,
                         field_width,
                         precision,
                         flags);
                 break;

             case 'd':
             case 'i':
                 flags |= SIGN;
             case 'u':
                 str = number(str,
                         va_arg(args, unsigned long),
                         10,
                         field_width,
                         precision,
                         flags);
                 break;

             case 'n':
                 ip = va_arg(args, int *);
                 *ip = (str - buf);
                 break;

             default:
                 if (*fmt != '%') {
                     *str++ = '%';
                 }
                 if (*fmt) {
                     *str++ = *fmt;
                 } else {
                     --fmt;
                 }
                 break;
         }
    }
    *str = '\0';
    return str - buf;
}


